From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C373C433DF for ; Wed, 19 Aug 2020 15:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36E1D207FF for ; Wed, 19 Aug 2020 15:18:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cV1u7p0w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728749AbgHSPSA (ORCPT ); Wed, 19 Aug 2020 11:18:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726899AbgHSPR0 (ORCPT ); Wed, 19 Aug 2020 11:17:26 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAC3FC061342; Wed, 19 Aug 2020 08:17:26 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id 2so1251757pjx.5; Wed, 19 Aug 2020 08:17:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=zmZ0nR+0stasAUqGKga9eB9ZFWY9muOXfNZAhE4dBCo=; b=cV1u7p0wvXmqtQLXfxc15Ws4Qo4Zt6uUGQKQdnWwMiD37QPnpsYZ35tUxZW0DLjC2F +DRi5ji/RLdDM5HuTLrg/vCsSsZSIr6f5Y/sG6t3cHpJsMcZJABAyXLH0INlx2A1IQu1 3HOcqdKTiqaVmjLVvF1LqSYOn4IjbEqAfyzY5pVuanO01IeEzMcJGd0jBFJrjAbks2TV PfbjuFX4KkVmeoNUatXXTq9sbXlWbvfmIGeCSCxKNMOnUN8ni6M9HyGDqjcD/PKfHVcr haMoVmXzA9dWws5GrRZemCI1FNXhC+9VcZwhEnPuDE+Hj+0zrnjO1jE595bSr3jFEtiu xrJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=zmZ0nR+0stasAUqGKga9eB9ZFWY9muOXfNZAhE4dBCo=; b=r3HQV7LH//YpR95iVvyTzHeljd+zdFa+hwiKNQIrs/3Op/kgg/ZkDyEDs9YpY2xBVT lu3aZK8OOrwcrWTRTze3spz0G94OFAICPTzQ4OohiR+Wf8gqADiTPtStHfSCgUGGnKBO 9/BCM6SNNMkGsJHFWrDZIUclwb08F/OiXU0BS4WRs82gZ7HG9m0c2c3KLVhflcIr/aRJ LBCF7+yDEbM97Qqn0eZFQOSu8hqLSCC1Wk/1npRvsTK9a1af6FXU7WsOV966DtAyYm9z tM9qNJJx6gugiQyVjNkrnAonJcae+5Fti9pTaZJsbenR/XwUD5Y02xnlTF7Jd5F7hIf2 ZNbA== X-Gm-Message-State: AOAM533rHsTkFDpgbcFIr84q7nuBtTniIs7hHJZLroZefvIq3b8G4fht jQMXoX+DeyeXadpHfBP9vw== X-Google-Smtp-Source: ABdhPJyIOb9pNzAosEPNXQ9tef9OxRKUmm6zMqaUbTiiSDJ2RtWwlz1pjDLcFQ9c9klXpmg53OhF9A== X-Received: by 2002:a17:902:eb51:: with SMTP id i17mr19791500pli.278.1597850246185; Wed, 19 Aug 2020 08:17:26 -0700 (PDT) Received: from PWN ([2600:3c01::f03c:91ff:fe6e:64cd]) by smtp.gmail.com with ESMTPSA id g23sm28739438pfo.95.2020.08.19.08.17.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2020 08:17:25 -0700 (PDT) Date: Wed, 19 Aug 2020 11:16:56 -0400 From: Peilin Ye To: Hans Verkuil Cc: Greg Kroah-Hartman , linux-media@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [Linux-kernel-mentees] [PATCH] v4l2-tpg: Fix global-out-of-bounds read in precalculate_color() Message-ID: <20200819151656.GA106705@PWN> References: <20200810050532.640075-1-yepeilin.cs@gmail.com> <774bcf2d-c8eb-086a-3569-c7e530d8a63d@xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <774bcf2d-c8eb-086a-3569-c7e530d8a63d@xs4all.nl> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mr. Verkuil, On Wed, Aug 19, 2020 at 04:26:28PM +0200, Hans Verkuil wrote: > Hi Peilin, > > On 10/08/2020 07:05, Peilin Ye wrote: > > precalculate_color() is reading out of `sin` since `tpg->hue` is not being > > properly checked. Fix it. `cos` is safe, as long as `tpg->hue` is higher > > than or equal to -192. > > Thank you for this patch, but there is something I don't understand, namely > just *how* tpg->hue can be out-of-range. > > From what I can see vivid sets hue via tpg_s_hue() when the V4L2_CID_HUE control > is set. But that control has a range of -128...128, so ctrl->val should always be in > that range. > > I would really like to know 1) what the value of tpg->hue actually is when it goes > out of range, and 2) who is changing it to that value. Can you do a bit more digging? Sure, of course! I will try to figure that out first. Thank you, Peilin > That said, it makes sense that precalculate_color() avoids reading out-of-bounds. > > > > > Fixes: 63881df94d3e ("[media] vivid: add the Test Pattern Generator") > > Reported-and-tested-by: syzbot+02d9172bf4c43104cd70@syzkaller.appspotmail.com > > Link: https://syzkaller.appspot.com/bug?id=db50123c788e2cc5a9d90de569c398b66293ee48 > > Signed-off-by: Peilin Ye > > --- > > drivers/media/common/v4l2-tpg/v4l2-tpg-core.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c > > index 50f1e0b28b25..52205fe096f7 100644 > > --- a/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c > > +++ b/drivers/media/common/v4l2-tpg/v4l2-tpg-core.c > > @@ -930,6 +930,9 @@ static void precalculate_color(struct tpg_data *tpg, int k) > > /* Implement these operations */ > > int tmp_cb, tmp_cr; > > > > + if (tpg->hue < -128 || tpg->hue > 128) > > + return; > > Rather than returning here, I prefer to just clamp tpg->hue to the valid range. > > I'd be willing to merge a patch that clamps tpg->hue (it certainly doesn't hurt), > but I also would like to understand how it can be out of range in the first place. > I have the feeling that this is a symptom of another problem elsewhere. > > Regards, > > Hans > > > + > > /* First convert to YCbCr */ > > > > color_to_ycbcr(tpg, r, g, b, &y, &cb, &cr); > > >